A senior costs judge has cut the £105m costs claimed by London firm Leigh Day & Co following its action against oil company Trafigura.

In a preliminary judgment last month, Master Hurst reduced the success fee that the firm can claim under the conditional fee agreement from 100% to 58%.

Leigh Day & Co obtained a group litigation order in 2006 to represent 30,000 claimants who were residents of the Ivory Coast. The residents claimed they had sustained physical injuries as a result of exposure to toxic waste that they claimed had been illegally dumped by a contractor of Trafigura around the capital Abidjan.

Trafigura did not accept liability, but the case settled in September 2009, just before the trial, with each claimant receiving about £1,000. Costs were awarded against Trafigura.

Following the settlement, Leigh Day & Co submitted its bill of costs to Trafigura, represented by City firm Macfarlanes. Trafigura challenged the sums claimed, particularly in relation to the success fee, witness statements, the cost of medico-legal reports and the number of experts’ reports obtained by the claimants.

The final costs hearing is expected to take place in May. Both Leigh Day & Co and Macfarlanes (on behalf of Trafigura) declined to comment.